Attempts to solve the problems of cold engine start up and associated adverse engine wear, and delayed provision of warm air to the passenger compartment have been made. These attempts cover simple heaters as well as elaborate integrated systems.
For example, U.S. Pat. No. 3,853,270 discloses an insulated storage tank located in series with the existing coolant system between the water pump and the passenger compartment heater. The tank has a volume at least equal to the volume of the entire coolant system and contains valves that operate automatically to store coolant heated by the engine during normal operation. The heated and stored coolant is recirculated when the engine is restarted. This system, however, cannot heat the coolant independently of the engine; therefore, the temperature of the coolant in the reservoir will decrease over time to the point where it is at ambient temperature.
U.S. Pat. No. 3,969,605 discloses an in-line coolant pre-heater reservoir containing an electrical heater. The pre-heater uses a pair of one-way valves that operate intermittently based upon the temperature of the coolant in the reservoir thus pumping the coolant that is heated in the reservoir throughout the entire coolant system. This system is not designed to rapidly heat the passenger compartment on engine start-up, but rather keeps the coolant at an elevated temperature while the engine is not operating. When in operation, the device has to raise the pressure in the coolant line such that the temperature of the coolant reaches its boiling point.
U.S. Pat. No. 4,208,570 discloses a flow through electric heater that is placed in series with the coolant line hose. A thermal bridge links the heating elements with the outer jacket of the heater thus lowering the jacket temperature of the heater during heater operation. This is simply an in line heater, and does not specifically act to heat the coolant rapidly upon engine start-up.
U.S. Pat. No. 4,454,984 discloses an auxiliary electric pump in the coolant line that continues to circulate warm coolant through the passenger compartment heater after the automobile engine is shutdown. The auxiliary pumping system will not operate when the engine is running, the voltage in the power supply of the vehicle is insufficient, or the coolant temperature is below a specified minimum temperature. The electric pump cannot heat the coolant upon engine start-up.
U.S. Pat. No. 4,532,894 discloses the use of an additional electric water pump, fuel powered heater powered by an auxiliary fuel source, and an electrically powered heat exchanger in series with the coolant line. The system is used to heat the coolant in a vehicle that is powered by both an electric and internal combustion engine. This is an elaborate system that uses both electricity and an auxiliary fuel to heat the coolant.
U.S. Pat. No. 5,012,070 discloses an elaborate passenger compartment preheating system for use on a parked vehicle that uses an external power source to power and electric heater disposed in a separate coolant line. The external power source also powers the heater core fan and an additional water pump. The external power is supplied through a plug and electric cord from a typical house wall outlet. Preheating of other components such as the engine itself is may be accomplished through the installation of additional heaters. The entire system is controlled by a operator programmed timer control unit and must be shut down and disconnected prior to vehicle operation. The system, however, needs an external power supply, and, therefore, can only operate when the engine is off and the car is parked.
U.S. Pat. No. 5,291,960 discloses a system for selectively using the energy produced during regenerative braking of a hybrid engine powered vehicle to recharge the batteries, pre-heat the internal combustion engine, or heat the passenger compartment. Both an electric heater and a heat storage battery are used. The internal combustion engine of this invention is used to run a generator to recharge the batteries. This system requires a heat storage battery and a heater that operates on regenerative braking, not upon internal combustion engine start-up.
U.S. Pat. No. 5,407,130 discloses a heat storage device in series with the engine coolant line. The storage device transfers heat that was stored from previous motor operation to engine coolant on engine start-up to heat the passenger compartment and the engine. This only permits storage of heated coolant, not the heating of the coolant.
U.S. Pat. No. 5,408,960 discloses an in-line electric heater with integrated pump and thermostat for preheating the liquid cooled internal combustion engine of a parked automobile prior to running the engine. The heater is placed in-series in an existing coolant line hose and uses household current to power the heater and pump. This operates only prior to engine start-up and the unit must remain plugged into an outlet to keep the coolant hot.
U.S. Pat. No. 5,333,679 discloses an automobile climate control system which uses a hydraulic pump driven by the engine to produce a working oil under pressure and a hydraulic relief valve to convert the pressure energy of the oil into thermal energy. The thermal energy is then transferred to the engine coolant which is then circulated through a heat exchanger to heat the passenger compartment. This system does not rapidly heat the coolant on engine start-up.
The present invention overcomes the limitations of the prior art by providing a simple and automatic method for more rapidly heating both the engine and passenger compartment of an automobile upon engine start-up that can be easily retrofitted into any existing coolant line and is powered by the existing engine current.